Indicating mechanism for ignition interrupters



May 6 1941- w. E. scHwARzMANN 2,240,804

INDICATING MECHANSM FOR IGNITION INTERRUPTERS Filed May 28, 1940 /7/ 7 ILL-G: 2

ATTORNEY Patented May 6, 1941 UNTED STATES PATENT OFFICE INDICATING RECHANISM FOR IGNITION INTERRUPTERS Application May 28, 1940, Serial No. 337,659

Claims.

The present invention relates to indicating mechanism for cam-operated circuit interrupters for ignition generators such as magnetos and such as timer distributors associated with battery ignition coils, and more particularly to such mechanism for indicating, solely and directly whenever the generator is at rest and Whether or not it is installed on an engine, the p-resence and extent of the wear of parts of the interrupter such as cause a variation in the angular relationship between a normally stationary part of the generator and that rotor of the generator which carries the rotatable element of the interrupter.

It has been customary to use a separate tool, as a. straight edge or the like, to determine this relationship but trouble sometimes occurred from inaccuracies in manually setting the tool each time and sometimes from absence or loss of thev tool when needed. Thus even if the reading were obtained, it was often erroneous to such a degree that the resetting of the interrupter contacts in accordance therewith appreciably reduced the power output, and detracted from the dependability =and life, of the internal combustion engine with which such ignition generator was associated. This is particularly important in the case of aviation magnetos having fixed ignition and requiring a high degree of effectiveness and reliability for safety and speed under extreme variations of altitude and other influencing factors. Also, spark indicators separate from the generator have been used to determine the angular positions of the sparking periods, but such an indicator requires test equipment having driving mechanism correlated to the speed and angular position of the generator and is not adapted for quick or convenient application to a generator that is or is not installed on an engine.

The primary object of my invention is to provide for such ignition generators, indicating mechanism forming a permanent part of the generator for indicating solely and directly the presence and extent of the wear of the parts of the interrupter resulting in a Variation from a predetermined angular relationship between a normally stationary part of the generator and that rotor of the generator which carries the rotatable element of the interrupter, when the generator is at rest and Whether or not it is installed on an engine. More specifically, this predetermined angular relationship is usuallyv that between the interrupter cam o-r the rotor on which it is mounted, on the one hand, and

a normally stationary part of the generator, on

the other hand, at the instant the contacts of the interrupter are separated a predetermined extent which is the minimum extent at which the circuit including them is just interrupted but may be any other desired value between the extreme positions of the movable contact with respect to the normally fixed contact. The mprovements in ignition generators by which this and other objects are attained will be obvious from the following description in connection with the accompanying drawing which show, as an example, the preferred form of my indicating mechanism for a high tension fixed-ignition aviation magneto having a cam fixed on the distributor rotor shaft in cooperation with a normally stationary interrupter of the deflectable lever type. In this drawing:

Fig. 1 is an end elevation, with the cover partly broken away, of the indicating and interrupting mechanism of my invention; and Fig. 2 is a section on line 2 2 of Fig. l.

In the drawing, the reference numeral I indicates the magneto intended to be fastened by a flange mounting 2 to an internal Icomlbustion engine which drives a magnetol rotor shaft 3, in this case the combined distributor rotor and interrupter shaft, properly timed to the cam shaft of the engine. The interrupter cam 4 is keyed or otherwise suitably fastened in proper angular position on shaft 3 and is held longitudinally thereon by the self-locking nut 5 with the indicating pointer 6 fastened therebetween in set angular rel-ation to the lobe 'I of the cam by means of diametrically offset slots 4 in the end face of the cam in which t the pointer 6 and its tail portion 6. This lobe 'I has a mark thereon as shown for its ready identification in using the indicator as hereinafter described. The peripheral wall 8 of the interrupter housing 9, which is fixed in position for this fixed-ignition magneto, has a V-slot or other suitable index ID cut along its interior wall surface in position to be directly and accurately observable in proximate registry with the end of the pointer 6 when the cover I I is removed. As will be understood, this cover is fastened in place over the open end of the interrupter housing in any -suitable way as by screws such as I2 and carries the usual ventilator I3, the rotor shaft 3 terminating in the housing.

The cooperative circuit contacts I4 and I5 of the circuit interrupting mechanism are stationary in their angular position in the interrupter housing, one being carried by the deflectable spring lever I6 and the other being fixedly mounted on the upstanding arm II of the adjustable bracket of which its base member I8 is normally held rmly on the interrupter plate I9 by the locking screw 28. When desired, however, the contact I may be moved between the guides 2| to adjusted position toward or away from the cam 4 by first loosening the locking screw and then turning the eccentric headed screw 22 in the engaging slot 23 in the well known manner. The spring lever I6 is iixed at one end to the interrupter terminal 24, fastened on the plate I9, and has at its other or outer end an abutment 25 which resiliently rests on the outer end of the cam follower or rubbing block 26. This block is fastened near the outer end of a pivoted lever 2l and the spring 28 assists in holding its inner end continually in engagement with the peripheral surface of the cam 4. The interrupter plate I9 is fastened to the interrupter housingr 9 by screws I9 passing through adjusting elongated holes as shown, and also carries the condenser 29 grounded to it and electrically connected by conductor 38 to the interrupter terminal 24 and the magneto short circuiting spring 3 I.

It will be observed that the pointer E is bent outwardly so as to be freely and permanently rotatable in the interrupter housing 9, with its outer end in proximity to the wall 8 thereof, whether or not the cover I I is in place, and also is pointed so as to assure accurately its position of registration with the index I8, so as to provide a registerable relation between the pointer and index, that is such a relation as does not require the use of a separate tool in determining the wear of the interrupter parts. The cam 4 and the cooperative circuit contacts are so assembled and fixed in position with relation to the rotor shaft 3, that the cam separates the contacts about 0.009 inch when the poles of the magnetic rotor and stator have an edge distance of about 2 to 2.5 mm., that is when the trailing edge of one magnetic rotor pole has moved away from the trailing edge of a cooperative stator pole by that chord distance, at which instant, as is well known, the magneto gencrates substantially its most effective ignition voltage. This is accomplished when assembling the magneto, either initially or after overhauling, by first setting the contact I5 for the normal extent of opening, and then fastening the interrupter plate I9 in that position in interrupter housing 9 at which pointer 6 exactly registers with index I0 when lobe 1 holds contact I4 off contact I5 by a separation of 0.009 inch or any other predetermined opening. If thereafter the cam, or the cam follower' 26 or the contacts I4, I5 become worn so that this relationship is altered, the predetermined position of maximum effectiveness of ignition may be reestabiished by turning the rotor shaft 3 until the pointer 6 registers with the index I0, and then adjusting the normally iixed contact I5 in the manner before explained until the proper separation of the cooperative contacts exists. This amount of separation of 0.009 inch, or whatever else is predetermined, may be ascertained by a feeler gauge between the contacts, or by a bell or lamp circuit connected between them, or by earphones or a meter or electronic tube associated with an impedance balanced circuit, or in any other suitable way.

It will now be understood that, in accordance with .my invention, the position of maximum eiectiveness of ignition may be accurately established and reestablished at any time, with the magneto at rest whether or not installed on the engine, by means of this indicating mechanism which is permanently installed on and continually operative with the magneto. Obviously, if desired, a plurality of index marks may be provided for the plurality of cam lobes, instead of one such mark for a selected lobe, and also the indicating mechanism may be used with magnetos having a timing range, instead of fixed tlming, by providing index marks for any or all of the retarded and advanced positions desired. Thus while I have shown but a single embodiment of the invention, it will be apparent that various other embodiments are within the scope of my invention in application to ignition generators in general such as timer distributors as well as magnetos of any suitable type, having various kinds of cams, whether rotary or stationary, and various kinds of interrupters actuated thereby. All such indicating mechanism of these kinds associated with interrupter mechanism of any suitable kind in all suitable rotary, oscillating or other form of single or multicylinder ignition generators are intended to be covered within the broad terms of the appended claims.

Having thus described my invention, what I claim is:

l. In combination with an ignition generator having a rotor, a normally stationary structure associated with said rotor, and circuit interrupting mechanism comprising cooperative contacts constituting one element thereof and a cam for intermittently separating them constituting the other element thereof, one of said elements being carried by said rotor and the other being normally stationary, of indicating mechanism permanently associated with said rotor for indicating at rest at a predetermined extent of separa` tion of said contacts by said cam the presence and extent of the wear of parts of said interrupting mechanism, solely and directly, such as would cause a variation in the angular relationship between said rotor and said structure, said indicating mechanism comprising a pointer member and an index member of which one member is fastened to the rotor carrying the rotatable element of the interrupting mechanism and of which the other member is permanently associated with said structure in proximate registrable relation with the first member.

2. In combination with an ignition generator having a rotor, an interrupter housing in which said rotor terminates, and circuit interrupting mechanism in said housing comprising cooperative contacts constituting one element thereof and a cam for intermittently separating them constituting the other element thereof, one of said elements being carried by said rotor and the other being normally stationary and arranged in said housing, of indicating mechanism in said housing and permanently associated with said rotor for indicating at rest at a predetermined extent of separation of said contacts by said cam the presence and extent of the wear of parts of said. interrupting mechanism, solely and directly, such as would cause a variation in the angular relationship between said rotor and said housing, said indicating mechanism comprising a pointer member and an index member of which one member is fastened to the rotor carrying the rotatable element of the interrupting mechanism and cf which the other member is permanently associated with said housing in proximate registrable relation with the first member.

3. In combination with an ignition generator having' a rotor, a normally stationary structure associated with said rotor, and circuit interrupting mechanism comprising cooperative contacts carried by said stationary structure and a cam carried on said rotor for intermittently separating said contacts, of indicating mechanism for indicating at rest at a predetermined extent of separation of said contacts by said cam the presence and extent of the Wear of parts of said interrupting mechanism, solely and directly, such as would cause a Variation in the angular relationship between said rotor and said structure, said indicating mechanism comprising a pointer fastened to said rotor for rotation therewith and an index carried by said structure in proximate registrable relation with said pointer.

4. In combination with an ignition generator having a rotor shaft, an interrupter housing, and circuit interrupting mechanism in said housing comprising normally stationary cooperative contacts and a cam mounted on said shaft for intermittently separating them, of indicating mechanism in said housing for indicating at rest at a predetermined extent of separation of said contacts by said cam the presence and extent or the wear of parts of said interrupting mechanism, solely and directly, such as would cause a variation in the angular relationship between said rotor and said housing, said indicating mechanism comprising a pointer fastened to said cam and an index associated with said housing in proximate registrable relation with said pointer.

5. In combination with an ignition generator having a rotor and also having a normally stationary structure with circuit interrupting mechanism comprising an adjustably fixed contact, a deectable contact cooperative therewith, and a cam for intermittently separating said deectable Contact from said xed contact, said contacts constituting one element and said cam constituting another element one of which is mounted on said rotor, of indicating mechanism permanently associated with said rotor for indicating at rest at a predetermined extent of separation of said contacts by said cam the presence and extent of the wear of parts ci said interrupting mechanism, solely and directly, such as Would cause a Variation in the angular relationship between said rotor and said structure, said indicating mechanism comprising a pointer member and an index member of which one member is fastened to the rotor carrying the rotatable element of the interrupting mechanism and of which the other member is permanently associated With said structure in proximate rgistrable relation with the first member, said adjustable fixed contact having means for adjusting it relatively to said cam tc adjust the exent of separation of said contacts when the indicating members are in registry.

WOLFGANG E. SCHWARZMANN. 

